Bad news for friendly doctors: the British Medical Association says medical staff and students shouldn't become Facebook friends with their patients.

New guidance, published today, warns about two key issues: getting too pally with patients, and posting "informal, personal or derogatory comments" about them on social media websites.

You'd think medical professionals would be smart enough not to post "OMG Fred Smith has a horrible bum disease LOL" or "Dammit! I've left my Rolex inside Mrs Addison!" in public forums, but you'd be wrong: The Guardian reports that the Nursing and Midwifery Council recently published similar guidelines after uncovering cases of "improper use" of Facebook.

It's not just doctors, either. Teachers have been disciplined over "inappropriate use of their personal accounts on social networking sites", and the National Association of Head Teachers (NAHT) worries that teachers need clear guidelines on what they should and shouldn't do online.

People are rubbish

It doesn't matter whether you're a brain surgeon or a park keeper: if your job has even the slightest element of responsibility, you should assume that the entire internet is out to get you. Imagining that your Facebook friends include at least one disguised News International journalist, an angry ex and a colleague who's trying to get you sacked concentrates the mind wonderfully.

You should fear the worst from friend requests, too. Does Mrs Boggs want to be your Facebook friend because she's keen to get an insight into the life of a medical pro, or is she going to bombard you with direct messages about her piles for eternity? Do your pupils want to be your friend because you're a really awesome teacher, or is it because they're hoping to get some pics of you dressed as Lady Gaga?

This should all be common sense, but unfortunately sometimes common sense gets overruled by ego. Instead of assuming the worst, we assume the best - so we interpret a friend request as "they like me! They really, really like me!" instead of a fishing expedition, and we worry more about getting a laugh than about protecting patients' or pupils' privacy.

The moral is simple: don't post anything online you wouldn't want quoted in a disciplinary hearing, and when you receive a new friend request, think back to the last time you saw them. Were they wearing a uniform, or were you wearing rubber gloves? If the answer is yes, think before you click.

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